This application claims the priority of commonly owned copending German patent application Serial No. 100 36 503.5 filed Jul. 27, 2000. The disclosure of the above-referenced German patent application, as well as that of each US and foreign patent and patent application identified in the specification of the present application, is incorporated herein by reference.
The present invention relates to improvements in apparatus for damping vibrations between rotary driving and driven parts, such as between the output shaft of an engine or another prime mover and the input shaft of a change-speed transmission in the power train of a motor vehicle. As a rule, such apparatus comprise first and second rotary torque transmitting devices and a torque transmitting and stray movements (such as vibrations) suppressing (damping) unit between such devices.
Torsional vibration damping apparatus of the character to which the apparatus of the present invention pertain are disclosed, for example, in published German patent applications Serial Nos. 199 12 970 A1, 199 09 044 A1, 196 48 432 A1, 196 03 248 A1 and 41 17 584 A1. All such parts or groups of parts in the apparatus of the present invention which are adequately disclosed and illustrated in the above-enumerated and other published German patent applications as well as in US and foreign patents granted to the assignee of the present application and/or to others will be described only to the extent necessary to readily locate the relevant references for additional disclosure (if necessary).
Damping apparatus of the type to which the apparatus of the present invention pertain are also disclosed in commonly owned German patent application Serial No. 100 37 107.8, filed Jul. 27, 2000, and in the corresponding copending U.S. patent application Ser. No. 09/915,817, filed Jul. 25, 2001 for xe2x80x9cAPPARATUS FOR DAMPING TORSIONAL VIBRATIONSxe2x80x9d.
A drawback of many presently known vibration damping apparatus is that they are not effective under any and all circumstances which arise in torque transmitting machines, assemblies or apparatus, as well as that they are in part too bulky, complex and expensive. Moreover, many (if not all) presently known torsional vibration damping apparatus are overly sensitive to the presence and influence of foreign matter, primarily or frequently because their sensitive constitutents are not adequately shielded against penetration of dust and/or other impurities and/or against uncontrolled escape of lubricant.
An object of our present invention is to enhance the simplicity and reliability as well as to reduce the initial and maintenance cost of torsional vibration damping apparatus, for example, of apparatus which can be put to use in the power trains of motor vehicles.
Another object of the instant invention is to provide torsional vibration damping apparatus which can be installed in existing power trains of motor vehicles or the like as superior substitutes for conventional apparatus of such character.
A further object of the invention is to provide novel and improved means for reliably confining grease, oil or another suitable lubricant in the enclosure(s) for the torsional vibration damper or dampers of the above outlined apparatus.
An additional object of the invention is to provide novel and improved means for shielding the sensitive constituents of torsional vibration damping apparatus from adverse influences of dust and/or other foreign matter.
Still another object of our present invention is to provide novel and improved seals for use in torsional vibration damping apparatus of the above outlined character.
A further object of the invention is to provide a power train, particularly for use in a motor vehicle, which embodies a torsional vibration damping apparatus of the above outlined character.
Another object of the present invention is to provide a novel and improved apparatus which is designed to transmit torque between the rotary output element of the engine and the rotary input element of the transmission in the power train of a motor vehicle, such as a passenger car, a truck, an SUV and/or others.
A further object of the invention is to provide a torsional vibration damping apparatus which is or which can be constructed and assembled in such a way that it can be readily converted for optimal operation under any one of a host of different circumstances.
An additional object of the invention is to provide novel and improved damper means for use in the above outlined apparatus.
Still another object of the invention is to provide the above outlined apparatus with novel and improved means for reliably coupling various constituents of the apparatus to each other.
A further object of the invention is to provide a novel and improved multi-stage torsional vibration damping apparatus for use in the power trains of motor vehicles and the like.
An additional object of the invention is to provide a novel and improved torsional vibration damping apparatus which can be readily assembled into a module for convenient and time-saving installation in the power train of a motor vehicle.
Another object of the present invention is to provide a novel and improved method of limiting or preventing stray movements of parts which transmit torque between a prime mover and a torque receiving unit, such as in the power train of a motor vehicle.
One feature of our invention resides in the provision of an apparatus for damping torsional vibrations, particularly in the power train of a motor vehicle (e.g., between the crankshaft or camshaft of the combustion engine or the output shaft of another prime mover and the input shaft of the manual, automated or automatic change-speed transmission). The improved apparatus comprises first and second torque transmitting devices which are turnable with and relative to each other about a common axis and are respectively arranged to normally receive torque from a rotary output element of a driving unit (such as the camshaft or the crakshaft of the aforementioned combustion engine) and to transmit torque to a rotary input element (such as the input shaft of the aforesaid transmission). The improved apparatus further comprises a damper which is constructed, assembled and installed to yieldably oppose rotation of the torque transmitting devices relative to each other and includes elastically deformable energy storing means engageable by suitably configurated and/or dimensioned and/or installed portions of the torque transmitting devices, and inserts which are interposed between the aforementioned portions of the torque transmitting devices on the one hand and the energy storing means on the other hand. The inserts have portions or sections (hereinafter called anvils for short) which are arranged to abut each other in response to turning of at least one of the torque transmitting devices relative to the other device through predetermined angles. The energy storing means is disposed at a first radial distance from the common axis of the torque transmitting devices, and the anvils are disposed at a lesser second radial distance from the common axis.
At least one but preferably each of the torque transmitting devices can include at least one flywheel. The arrangement can be such that the improved apparatus comprises first and second flywheels which are rotatable about the common axis of the torque transmitting devices, and means for respectively connecting the first and second flywheels to the first and second torque transmitting devices.
The energy storing means can include at least two arcuate or polygonal (hereinafter often referred to as arcuate) resilient components having centers of curvature at (i.e., on or relatively close to) the common axis of the torque transmitting devices and being arranged to permit the two devices to turn relative to each other clockwise and counterclockwise from a neutral position through angles of at least 30xc2x0. The arcuate resilient components can include or constitute coil springs, and the coil springs of at least one of the resilient components can be arranged to undergo expansion and/or contraction.
The energy storing means of the damper can include at least one arcuate resilient component having a series of coil springs which are disposed end-to-end. The at least one arcuate resilient component can constitute or include at least one elongated precurved coil spring.
It is also possible to employ energy storing means which includes at least one set of interfitted coil springs.
At least a portion of at least one of the inserts can consist of a plastic material.
The apparatus can further comprise means for securing the end portions of the energy storing means to the aforementioned portions of the torque transmitting devices against unintentional separation of such devices from the energy storing means.
As already mentioned hereinbefore, the energy storing means of the damper can include a plurality of elongated arcuate resilient components having centers of curvature at the common axis of the torque transmitting devices. The inserts are or can be grouped into pairs, one pair for each resilient component, and the anvils of at least one pair of inserts are inwardly adjacent the respective resilient component of the energy storing means of the damper. The anvils of the at least one pair of inserts can extend along arcuate paths and the anvils of each pair can have a combined length less than the length of the respective resilient component in a condition the at least one component assumes in predetermined starting positions of the torque transmitting devices relative to each other. The inserts of the at least one pair of inserts can further include radially outwardly extending portions which are adjacent the end portions of the at least one coponent of the energy storing means. Each radially outwardly extending portion can exhibit at least some elastic deformability.
The improved apparatus can further comprise additional damper means which is arranged to yieldably oppose turning of the torque transmitting devices relative to each other upon completion of turning of the torque transmitting devices relative to each other through the aforementioned predetermined angles. The damper can have a first spring gradient and the additional damper means can have a higher second spring gradient. Furthermore, or in addition to the just mentioned feature involving the spring gradients, the damper can exhibit a first moment of friction and the additional damper means can exhibit a higher second moment of friction. In accordance with a presently preferred embodiment, the damper has a first spring stiffness and a first moment of friction, and the additional damper means has a second spring stiffness and a second moment of friction; at least one of the second stiffness and the second moment of friction is higher than the corresponding characteristic(s) of the damper. It will be seen that, at least in many instances, the additional damper means exhibits at least one characteristic which is different from the corresponding characteristic of the damper; such at least one characteristic can constitute the stiffness of the additional damper means.
The anvils can be provided with end faces which are disposed in planes including the common axis of the torque transmitting devices. Alternatively, such end faces can constitute ramps which are inclined with reference to the aforementioned planes and abut each other in response to turning of at least one of the torque transmitting devices through the aforementioned predetermined angles. The ramps can be oriented and dimensioned and/or otherwise designed to enhance the damping action of the damper in response to abutment of the respective anvils against each other. In accordance with one presently preferred embodiment, the ramps are oriented to frictionally engage each other as soon as the anvils come into abutment with each other.
The anvils can be installed with at least some freedom of movement radially of the common axis of the torque transmitting devices so that they can bear upon the energy storing means of the damper under the action of centrifugal force in response to turning of the torque transmitting devices about their common axis.
Alternatively or in addition to the just discussed feature, the inserts can be arranged to bear upon at least one of the torque transmitting devices under the action of centrifugal force in response to turning of such devices about their common axis.
Still further, the anvils can be arranged to bear upon at least one of the energy storing means, the first torque transmitting device, and/or the second torque transmitting device under the action of centrifugal force in response to turning of the torque transmitting devices about their common axis.
One of the torque transmitting devices can comprise two axially spaced-apart sidewalls extending at least substantially radially of their common axis, and the other torque transmitting device can comprise a third wall or partition disposed between the two sidewalls. The one torque transmitting device is or can constitute the first torque transmitting device, i.e., the device which normally transmits torque to the second device by way of the damper. The arrangement can be such that the anvils bear upon at least one of the walls (i.e., upon at least one of the sidewalls and/or upon the third wall) under the action of centrifugal force in response to turning of the energy storing devices about their common axis.
The inserts can be arranged to establish a frictional engagement with the first torque transmitting device, with the second torque transmitting device and/or with the damper, and to thus generate a frictional damping action, at least in response to turning of the torque transmitting devices relative to each other. Such apparatus can further comprise at least one spring which is arranged to urge the inserts against the first torque transmitting device, against the second torque transmitting device and/or against the damper and to thus establish and maintain the aforementioned frictional damping action. The at least one spring can include or constitute at least one diaphragm spring (also called Belleville spring).
If at least one of the torque transmitting devices includes at least one flywheel which is rotatable about the common axis of the torque transmitting devices, at least one of the inserts can be arranged to oppose wobbling of the flywheel(s), e.g., to oppose wobbling of two coaxial flywheels relative to the common axis of the torque transmitting devices.
One of the torque transmitting devices can be designed to define an annular chamber for the energy storing means of the damper, and such apparatus can further employ a supply of lubricant (such as grease) which at least partially fills the chamber. The anvils of the inserts in such apparatus can include portions which constitute seals (or at leas partial seals) against the escape of lubricant from the chamber and/or against penetration of dust and/or other contaminants into the chamber.
If the energy storing means includes one or more coil springs, the improved apparatus can further comprise means for opposing rotation of at least one coil spring or each coil spring about its longitudinal axis.
As a rule, or at least in many embodiments of the improved apparatus, the torque transmitting devices are turnable relative to each other about their common axis in clockwise as well as counterclockwise directions. The energy storing means of this apparatus can include a plurality of springs which are arranged end-to-end; such springs can include at least one first spring having a first spring rate and being arranged to store energy in response to clockwise turning of the torque transmitting devices relative to each other, and at least one second spring which has a second spring rate and is arranged to store energy in response to counterclockwise turning of the torque transmitting devices relative to each other.
The energy storing means of the damper can include at least two arcuate resilient components, and the inserts of the apparatus employing such damper can further include portions disposed between the resilient components. The aforementioned portions of the torque transmitting devices preferably include extensions which are disposed between the resilient components, and such apparatus preferably further comprises auxiliary springs which are disposed between the extensions and the portions of the inserts. Such apparatus can further comprise means for securing the auxiliary springs to the aforediscussed portions of the inserts; the securing means can include form-locking connections. The torque transmitting devices of the just described embodiment of the improved apparatus are or can be turnable relative to each other in clockwise and counterclockwise directions, and the auxiliary springs can be arranged to store energy in response to turning of the torque transmitting devices relative to each other in the clockwise or counterclockwise direction. It is also possible to design the apparatus in such a way that at least one first auxiliary spring is arranged to store energy in response to clockwise turning of the torque transmitting devices relative to each other and at least one second auxiliary spring is arranged to store energy in response to counterclockwise turning of the torque transmitting devices relative to each other.
Another feature of the present invention resides in the provision of a torsional vibrations damping apparatus which comprises first and second torque transmitting devices turnable at least within limits relative to each other about a common axis, and means for yieldably opposing turning of the devices relative to each other; such opposing means includes at least one energy storing means and at least one hysteresis arrangement.
The apparatus preferably further comprises inserts which are interposed between portions of the torque transmitting devices one the one hand and the at least one energy storing means on the other hand. The inserts are provided with anvils which are arranged to abut each other in response to turning of at least one of the torque transmitting devices relative to the other device through predetermined angles.
The at least one energy storing means is disposed at a first radial distance from the common axis of the torque transmitting devices, and the anvils are disposed at a lesser second radial distance from such axis.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved torque transmitting apparatus itself, however, both as to its construction and the modes of assembling, installing and operating the same, together with numerous additional important and advantageous features and attributes thereof, will be best understood upon perusal of the following detailed description of certain presently preferred specific embodiments with reference to the accompanying drawings.